The progress of graphene research is growing very fast after the discovery of graphene in 2004. This is no doubt that commercialization of graphene will center in the future of graphene. The key challenge is the scale-up production of graphene or graphene-based materials. The hope has been lightened by several breakthrough results introduced above. However, the reproducibility is still concerned, as it is difficult to control the uniformity of individual graphene sheets from “top down” method. It also may be affected by the irregular edge of graphene and randomly dispersed functionalities on graphene sheets. The state-of-the-art techniques are also needed to achieve well-controlled microstructure of functionalized graphene and its derivatives. The article reviewed graphene functionalization and its application to polymer composite materials.